Positioning means and method of use thereof

ABSTRACT

A positioning device ( 13 ) for producing a light signal ( 32 ) to position a robot tool ( 2 ) relative to a workpiece ( 14 ) is provided. The positioning device ( 13 ) comprises a frame ( 16 ) and a pair of light sources ( 22, 24 ) mounted at the free end of the frame and arranged to direct a pair of light beams ( 28, 30 ) therefrom in converging directions which intersect with each other and provide a light signal ( 32 ) at a predetermined distance from the free end of the frame ( 16 ). The positioning device ( 13 ) can include two pairs of light sources to generate two pairs of intersecting light beams ( 28, 30; 29, 31 ). The two pairs of light sources can be arranged so that the two pairs of light beams ( 28, 30; 29, 31 ) are located substantially 90 degrees apart.

This invention relates to positioning means and a method of use thereof.

Although the following description refers almost exclusively topositioning means for use in positioning a robotic weld torch relativeto a weld seam or workpiece, it will be appreciated by persons skilledin the art that the positioning means of the present invention can beused to position any object, part or surface relative to a furtherobject, part or surface in use, such as in Mig, Mag, Tig and/or plasmacutting and/or the like.

Robotic weld torches are used in a number of different industries toallow precise automated welding of at least two objects, parts orsurfaces together. A typical robotic weld torch includes an arm memberhaving a first end which attaches onto the end of a robotic unit and asecond free end. A channel runs through the arm member and an elongatedelectrode wire is located in the channel. An end of the electrode wireprotrudes a short distance from the second free end of the arm memberand a wire feed system feeds wire through the arm member as the wire isconsumed during the welding process. A power source provides electricalcurrent to the electrode wire during use. Air or liquid cooling meanscan be provided with the torch to cool the welding apparatus. A furtherinert gas can be dispensed adjacent the second free end to act as ashield around the weld site to prevent the same from contamination whenthe weld pool is in a molten state. A removable shroud can be locatedaround the second free end adjacent the gas dispensing nozzle to ensurethe gas is focused onto the weld location. The welding torch can be usedas part of a fully automated or semi-automated welding system.

In order to join weld parts together, the individual parts must beprecisely aligned and held securely in place during the welding process.In addition, the robotic weld torch needs to be aligned precisely withthe parts being welded to provide an accurate weld. Conventionally,programming of the robotic weld torch by an operator to undertake awelding process involves the operator remotely moving the robotic torchalong a preferred path of welding. Once programmed, the welding torchthen follows the welding path set by the operator. If an incorrect weldpath is set by the operator, this can result in problems associated withthe weld bead, the weld throat, weld penetration, weld position and/orthe like, which could result in separation of the weld material. It istherefore essential that the operator is able to accurately position theweld torch on the welding path.

However, a problem associated with welding is that it is often difficultfor the operator to see the free end of the weld torch due to poor lightconditions, obstructions and/or the like, thereby resulting inmisalignment of the weld torch relative to a preferred welding path andpoor weld quality. The operator has to be trained and have a high levelof skill to precisely locate the weld torch on a correct welding path.As such, the positioning of the weld torch in terms of distance andangle of the torch relative to the workpiece is often susceptible tohuman error and requires expensive training to be undertaken by theoperator. In addition, the electrode wire protruding from the free endof the arm member often gets bent during programming of the weld torchon the weld path. As such, the operator has to frequently trim theelectrode wire to obtain the correct protrusion length. This is bothtime consuming for the operator and adds expense to the weld process. Inaddition, the operator may not realise the wire is bent and thusprogramme the weld path for a bent wire rather than the straight wirethat will be fed through the second free end during welding, thuscreating an incorrect weld path programme and poor weld quality.

It is therefore an object of the present invention to providepositioning means which increases the ease and reduces the skill levelrequired by an operator to accurately position apparatus associated withthe positioning means. It is also an object of the present invention toprovide improved weld quality.

It is a further object of the present invention to provide positioningmeans for use on a robotic weld torch.

It is a yet further object of the present invention to provide a methodof using positioning means.

According to a first aspect of the present invention there is providedpositioning means for positioning a first object, surface or partrelative to at least a second object, surface or part in use and whereinthe positioning means includes lighting means capable of generating atleast first and second light beams or light projections in use, thelighting means being arranged such that the light beams or lightprojections are directed away from the positioning means in a convergingdirection and said light beams or light projections intersect orsubstantially overlap with each other at a pre-determined distance fromsaid positioning means.

Although the term “lighting means” is used herein, this term also coversuse of an energy source or sources which are capable of emittingelectromagnetic radiation of pre-determined wavelength and which can bevisualised directly or indirectly with the human eye, such as radiationwith a wavelength in the visible part or optical part of the spectrum(i.e. approximately between 380-750 nm wavelength). For example, a laserbeam is often considered to be emitted from an energy source and theprojected light is seen as a dot or small shaped projection on a surfaceon which the beam is projected in use.

The pre-determined distance where the light beams intersect typicallycorresponds to a correct or operative position of the positioning meansfrom the first and/or second object, surface or part. When thepositioning means is used on a robotic welding torch the correct oroperative position at which point the light beams intersect typicallycorresponds to a weld seam between first and second weld parts.

Lens means or other focusing means can be used to direct and/or focusthe light beams or light projections in a converging direction. The lensmeans of focusing means can be provided on the positioning means orassociated therewith. However, in a preferred embodiment lighting means,such as for example a laser beam, are used which emit or project lightof a substantially well-defined, narrow wavelength to producesubstantially parallel beams of light from a single light source. Inthis embodiment lens means and/or other focusing means may not berequired. This is typically in contrast to an incandescent light sourcewhich emits light over a wider spectrum of wavelengths to providediverging light beams and lens and/or other focusing means are requiredto converge the light into a required direction.

Alternatively and/or in addition, the lighting means can be provided aone or more pre-determined spaced distances apart and/or at one or morepre-determined angles relative to each other to create the convergingbeams. For example, if laser beams or laser projections are used thelight sources can be set at a pre-determined angle to allow the lightbeams or projections to converge towards each other to allowintersection of the beams or projections at some pre-defined distance.

If the light beams intersect a distance before they hit a surface of anobject, part and/or the like, the beams will diverge away from eachother and will be projected onto said object, part and/or the like aspaced distance apart. As such, when two beams are projected onto aworkpiece, surface, object and/or part, a spaced distance between thebeams indicates that the positioning means is too close to the workpiecefor the beams to have yet intersected and the point of intersection willbe a distance behind the workpiece, surface, object and/or part; or thepositioning means is too far from the workpiece and the beams haveintersected a spaced distance in front of the workpiece and the beamsare now diverging after intersection.

At the point of intersection, the light beams substantially overlap,thereby forming a single light beam which can be easily seen by a useror detected by other suitable means, thereby informing the user or othersuitable means that a pre-determined distance of separation (i.e.position) of the lighting means from the first and/or second object,surface or part has been achieved. Alternatively, if different colouredlight beams are used, a further colour will be achieved at the point ofintersection as a result of mixing of the different coloured lightbeams.

Preferably the lighting means includes at least two separate ordifferent light sources to generate the at least first and second lightbeams. The light sources can be located at the same angle or differentangles relative to the housing or frame of the positioning means. Forexample, two pairs of light sources could be provided to generate twopairs of light beams. The angle and/or distance of separation of thelight sources for one pair could be different to the other pair, therebyallowing creating different light beam intersection points.

In one embodiment a part of light beams are used to provide a correct oroperative position in a particular plane. Thus, two pairs of light beamsallow orientation of the positioning means in at least two of the X, Yand Z planes. The two pairs of light beams also allow the positioningmeans to be oriented both horizontally in the X and Y directions andvertically in the Z direction.

In one example, four light beams could be generated. In a furtherexample, 6, 8, or even more, light beams could be generated as required.If the light beams are arranged in pairs, processing means could be usedto switch between the different light beam pairs. Different light beampairs could be set at different angles or heights in the positioningmeans relative to each other to allow different pre-determined operativedistances to be provided.

Thus, the pre-determined angle and/or distance of the lighting meansproviding the at least first and second visible light beams typicallycorresponds to the pre-determined or operative distance of separation ofthe positioning means or lighting means from the object, surface ofpart, thereby allowing the positioning means to accurately andreproducibly position apparatus associated with the positioning meansrelative to a required surface in use.

Preferably the light beams within each light pair are projectedsubstantially 90 degrees relative to a further light pair in thepositioning means.

The method of moving the positioning means to create the overlap of theprojected light beams in use is quick and easy, thereby reducing theskill level required by users to use the positioning means and apparatusassociated therewith and reducing the costs associated with incorrectpositioning of apparatus, objects, parts and/or surfaces. In addition,it provides an improved weld quality.

Preferably the positioning means includes a housing or frame which canbe integrally formed with, attached or detachably attached to apparatus,an object, part, surface and/or the like which needs to be correctlypositioned relative to a further object, part and/or surface.

For example, if the positioning means is to be attached to a roboticweld torch, the dimensions of the housing or frame can be substantiallythe same as a conventional shroud for the robotic weld torch, therebyallowing the housing or frame to be retrofitted to a conventionalrobotic weld torch.

The attachment means for attaching or detachably attaching thepositioning means can include a screw fitting, bayonet fitting, frictionfit, one or more screws, bolts, ties, clips, inter-engaging membersand/or the like.

If the positioning means is integrally formed and is to be used on aweld torch, the positioning means typically needs to be heat resistanceand may need to be formed such that weld wire can pass through thepositioning means.

In one embodiment the positioning means is for use on a weld torch, suchas a robotic weld torch, and the housing or frame is integral with,attached or detachably attached to a free end of the weld torch adjacentthe electrode wire. The housing or frame can have a first end withattachment means for attachment adjacent the free end of the weld torch,and a second end adjacent the electrode wire in or from which the lightbeams are projected.

Preferably a power source is provided to power the lighting means. Thepower source can be provided in or on the housing or frame of thepositioning means. In one embodiment the power source can be remote fromthe housing or frame and/or can be powered via a power source of theapparatus or weld torch on which the positioning means is to be used.

In a preferred embodiment the power source is in the form of at leastone battery and preferably at least one rechargeable battery. A dockingstation can be associated with the housing or frame to allow docking ofthe positioning means and/or a part thereof with the docking station toallow recharging of the power source.

The docking station cab can allow recharging via electrical contactsprovided on the docking station which are brought into engagement withcomplementary electrical contacts provided on the housing or frame ofthe positioning means. In a preferred embodiment, the docking stationcan allow recharging via induction with, for example, an induction coilprovided on the docking station into which the housing or frame of thepositioning means, which also has at least one induction coil providedtherein, is located. The use of recharging by induction is preferablesince it allows the housing or frame to be made as a substantiallysealed unit, more robust and reduce the risk of damage, contamination,ingress of water or dirt and/or the like therein.

Preferably the lighting means is in the form of a plurality of lightsources, such as laser beams, fibre optics, LEDs and/or the like. Eachlight source is typically provided a spaced distance apart from anadjacent light source in or on the housing, thereby allowing apre-determined distance or angle of light beams projected from the lightsources to be set. The light source can be located on, located in,recessed in the housing or frame or in any other manner providing two ormore light beams are emitted from or adjacent an end or a part of thehousing or frame.

In one embodiment adjustment means can be provided to allow adjustmentof the angle and/or distance of the lighting means or light source. Thisadjustment can allow the position, distance or angle of the lightingmeans relative to the housing of the positioning means, relative to anadjacent light source and/or a workpiece and/or the like to be changed,thereby allowing adjustment of the pre-determined or operative distanceat which the light beams will intersect or overlap. The adjustment meanscan allow adjustment to a user selected arbitrary position or allowsadjustment between two or more pre-determined positions.

For example, when the positioning means is used on apparatus, such as arobotic weld torch, the adjustment means could include a pin orprotruding arm on one of the housing and/or apparatus which is movablein a curved or arced slot on the other of the housing or apparatus inuse. In a further example, a plurality of removable spacing elements canbe used to change the separation distance of the positioning meansrelative to the apparatus. In a yet further example, a collet or movablejaw type of arrangement can be used. The movable jaw could include aplurality of jaw members located adjacent the second end of the housingor frame of the positioning means which are movable between open andclosed positions. Lighting means could be provided in the jaw members,such that movement of the jaw members adjusts the distance of thelighting means from the free end of the weld torch.

In a preferred embodiment, the adjustment means allows the position ofthe housing or frame of the positioning means, and thus the position ofthe lighting means, to be changed relative to the free end of a roboticweld torch. Thus, the adjustment means allows the distance of the torchfrom the workpiece, at the point where light beams will overlap orintersect, to be changed.

The adjustment means can be actuated manually, be semi-automated orfully automated as required. Processing means could be associated withthe lighting means to allow the lighting means to switch betweendifferent settings, positions and/or the switch between different lightbeam pairs.

The visible light beams can be any or any combination of colours. Forexample, the light beams could be the same colour or different colourscould be used, such that when the light beams overlap, they form afurther colour. In one example, different coloured light beams could beused to indicate positioning of the light beams associated with adifferent axis or plane, such as a X, Y and/or Z axis.

In one embodiment a further illumination source is provided to aidvisibility in the locality of use of the positioning means. The furtherillumination source is typically a different colour to the lightingmeans of the positioning means, thereby allowing an operator to moreeasily visualise the light beams. The further illumination source ispreferably a diverging source of light and is preferably located toproject outwardly from the second free end of the positioning means orweld torch.

Means could be provided to allow adjustment of the size, shape, focusand/or the like of a light beam. In one embodiment lenses with differentmagnifications can be associated with the light beams to allowadjustment of the size, shape and/or focus of the light beam.

Different sized and/or shaped positioning means could be used withdifferent sized and/or shaped apparatus and/or robotic weld torches.Alternatively, adaptor means could be provided to allow a positioningmeans to be used with a number of different sized and/or shapedapparatus and/or robotic welding torches. The adaptor means couldinclude an intermediate attachment member having a first end of suitabledimensions to fit the apparatus or weld torch and a second end ofsuitable dimensions to fit the positioning means thereto.

Sensing means could be associated with the positioning means and/orobject, part or surface to signal when intersection or overlapping ofthe light beams takes place or has not taken place. The sensing meanscould include any suitable visual, audio and/or kinaesthetic means. Thesensing means could be used to inform an operator or could be used withprocessing means to provide auto-correction of the positioning means.

In one embodiment a feedback system is provided, such that on detectionthat the light beams are not intersected, processing means automaticallyinstructs the apparatus associated with the positioning means to moveuntil intersection of the light beams is achieved.

Preferably control means are provided to allow control of the powersource and/or lighting means associated with the positioning means. Thecontrol means can move the power source and/or lighting means between onand/or off conditions and/or can move the lighting means between acontinuous lit position and/or one or more flashing light positions. Thecontrol means can be actuated manually or automatically. In one example,the control means is in the form of a switch which can be actuated by anoperator. In a further example, the control means includes one or moreelectrical contacts which, when brought into contact with one or moreother electrical contacts, automatically switches the lighting meansand/or power source to an on condition. Thus, in one example, when thehousing of the positioning means is fitted onto the end of a roboticweld torch, the lighting means is automatically switched from an “off”condition to an “on” condition.

Preferably alarm means can be provided to signal to an operator if theweld torch or apparatus is used or attempted to be used whilst thepositioning means is still attached thereto. This could prevent damageto the positioning means and/or apparatus if the operator forgot toremove the positioning means from the apparatus prior to use of theapparatus. In an alternative embodiment the positioning means isdesigned to remain on the apparatus or weld torch during normal use.

According to a second aspect of the present invention there is provideda method of using positioning means for positioning a first object,surface or part relative to at least a second object, surface or part inuse, wherein the method includes the steps of moving the positioningmeans relative to an object, part or worksurface in use until at leastfirst and second visible light beams generated by lighting meansassociated with the positioning means and projected onto said object,part or worksurface intersect and/or substantially overlap at anoperative point on said object, part and/or worksurface.

According to further independent aspects of the present invention thereis provided positioning means for a robotic weld torch; and a roboticweld torch with positioning means.

In one embodiment the positioning means is used in combination with oneor more light sensing means to detect the position of the lighting meansassociated with the positioning means and thus the positioning means. Assuch, the positioning means can be used as part of a positioning system.Preferably the light sensing means are provided in different positionsin the X, Y and/or Z plane and as the light beam passes over a sensor,the sensor is actuated.

According to a yet further aspect of the present invention there isprovided a positioning system, said positioning system includingpositioning means and a platform which the positioning means is requiredto be positioned relative to, the positioning means including lightingmeans capable of generating at least first and second light beams orlight projections in use, the lighting means being arranged such thatthe light beams or light projections are directed away from thepositioning means in a converging direction and said light beams orlight projections intersect or substantially overlap with each other ata pre-determined distance from said positioning means, the systemfurther including light sensing means on or associated with the platformto allow detection of the intersected or substantially overlapping lightbeams or projections in use.

Preferably the light sensing means include one or more sensors. Furtherpreferably the light sensing means are located in such a way that theyonly detect the light beams or projections when overlapped orintersected rather than single light beams. For example, the one or moresensors can be recessed a pre-determined distance below an upper surfaceof the platform or a housing located on the platform.

Preferably one or more side walls defining the inlet to the recessedsensor are angled or have a narrowing taper from the free end towardsthe sensor, thereby allowing a single dot or overlapping beams to befocused onto the sensor.

Further preferably a plurality of light sensing means are provided andtypically each sensing means is provided in each corner or required partof the platform.

According to a yet further aspect of the present invention there isprovided a training aid for training an operator to use the positioningmeans and/or apparatus associated with the positioning means.

When the present invention is used on a robotic weld torch, it has theadvantages of providing improved weld quality and consistency, fasterprogramming of the robotic torch by an operator, improved visibility ofthe weld area to an operator and can act as a training aid for anoperator.

In one embodiment, the positioning means of the present invention can beused to correctly position location pins used in the weld process. Theweld parts to be welded are typically provided with apertures thereonwhich are located over location pins provided on a weld platform orsurface in use to allow correct alignment of the weld parts relative tothe weld platform or surface. However, if the location pins are in anincorrect position, the weld path followed by the robotic weld torch islikely to be incorrect. The present invention can be used by an operatorto visually check the position of the location pins as the operatorwould be required to align/overlap the light beams, and preferably twopairs of light beams, on the centre of the location pin to ensure itscorrect position.

In a further embodiment, the positioning means of the present inventionis used to correctly position the weld platform on which the weld pinand/or weld parts are to be located in use. Positioning of the weldplatform typically requires use of the light sensing means as describedabove.

In a yet further embodiment, the positioning means of the presentinvention can allow an operator to check that the weld wire or “cast” isstraight and is not bent. The operator can do this by seeing if thelight beams projected onto the electrode wire substantially surround theelectrode wire (i.e. the electrode wire is substantially centrallylocated in the overlapped beams). If the wire is straight, theoverlapping beams will substantially equally surround the longitudinallength of wire (i.e. appear coaxial with the same). If the wire is bent,the longitudinal length of the wire will be offset from the overlappingcentre of the beams (i.e. will not appear coaxial with the same).

Embodiments of the present invention will now be described withreference to the accompanying figures, wherein:

FIG. 1 illustrates an example of a conventional robotic weld torchforming part of the prior art;

FIG. 2 a illustrates positioning means of the present invention in oneembodiment when connected to a conventional weld torch of the type shownin FIG. 1;

FIG. 2 b illustrates different positions of the light beams emitted fromthe positioning means in FIG. 2 a;

FIG. 3 shows an end view of the positioning means in FIG. 2 a;

FIGS. 4 a and 4 b illustrate incorrect alignment and correct alignmentof the positioning means relative to a workpiece respectively;

FIG. 5 illustrates a cross section of a positioning platform for usewith positioning means of the present invention according to oneembodiment;

FIG. 6 a illustrates a cross section of the positioning means of thepresent invention in use on the positioning platform in FIG. 5;

FIG. 6 b illustrates a plan view of a positioning platform for whichpositioning means can be used;

FIG. 7 illustrates adjustment means for use with positioning means ofthe present invention in one embodiment;

FIG. 8 a illustrates use of the positioning means for aligning locationpins used on a positioning platform;

FIGS. 8 b and 8 c show an example of correct positioning of thepositioning means with a location pin and incorrect positioning of thepositioning means with a location pin respectively;

FIGS. 9 a and 9 b illustrate a cross sectional view and end viewrespectively of a further embodiment of positioning means according tothe present invention; and

FIGS. 10 a and 10 b illustrate a yet further embodiment of the presentinvention in which an operator can check whether the weld wire is bentand straight respectively.

Referring firstly to FIG. 1, there is illustrated a prior art roboticweld torch 2 for welding two or more weld parts together. Torch 2includes an arm member 4 having a first end 6 for attachment to arobotic unit and a second free end 8 at which a nozzle 9 is located.

An electrode wire 10 located in a channel in arm member 4 protrudesoutwardly a pre-determined distance ‘L’ from free end 8. A removableshroud 12 is fitted onto arm member 4 adjacent second end 8 to allowgas, which is used to shield the welding process, to be directed ontothe area surrounding the weld.

Conventionally, positioning of the torch 2 relative to the work piece tobe welded is undertaken by an operator. However, thisalignment/positioning process is subject to human error which affectsthe quality and consistency of the weld.

In order to overcome this problem, positioning means 13 are providedwhich fit onto the second end 8 of torch 2 in place of shroud 12 toallow correct positioning of the torch end 8 from workpiece 14, as shownin FIGS. 2-4 b. More particularly, positioning means 13 is in the formof a shroud 16 which can fit onto arm member 4 in a similar manner toconventional shroud 12. A first end of the shroud 16 can be providedwith adaptor means for engagement with the end 8 of the welding torch 2.Shroud 16 has a channel 20 running therethrough to allow the free end 8and the nozzle 9 of arm member 4 to be located therein and to allow theweld wire to pass therethrough from the second free end of the armmember in order to check whether the wire is bent or straight. Inaccordance with the present invention, shroud 16 has lighting means inthe form of at least two laser diode light sources 22, 24 located at oradjacent the free end 26 thereof. The laser light sources 22, 24generate two light beams 28, 30 therefrom respectively. Furtherembodiments can contain more than two light beams and preferablymultiples of two light beams to form multiple light beam pairs as willbe described in more detail below. The laser diode light sources 22, 24can be located in recesses at or adjacent the free end 26 of the shroud16.

The distance between the light sources 22, 24 and the angle of the lightsources relative to each other is pre-determined, such that at apre-determined height ‘L’ of the light sources 22, 24 above workpiece14, the light beams 28, 30 emitted from light sources 22, 24 willsubstantially overlap to form a single light dot 32, as shown in FIGS. 2b and 4 b. This single light dot needs to be in precise alignment withthe weld seam 34 between workpiece 14 and workpiece 14′ to which it isto be welded. When a single light dot is formed by the two overlappingbeams, the operator will know that correct positioning of the weld torchrelative to the weld workpiece has been achieved. If the light sources22, 24 are too close to workpiece 14 (i.e. at a distance ‘a’), the lightsources 22, 24 will not have converged onto each other and will beprojected onto the workpiece a spaced distance apart, as shown in FIG. 2b. If the light sources 22, 24 are too far apart from workpiece 14 (i.e.at a distance ‘b’), the light sources will intersect each other at aspaced distance in front of work piece 14, as shown in FIGS. 2 b and 4a, and will be projected on the workpiece 14 a spaced distance apart.

Thus, when the light beams are a spaced distance apart on the workpiecethe operator knows the weld torch is not positioned correctly withrespect to the workpiece and can increase or decrease the height of freeend 8 of the weld torch from the workpiece until a correct height oroverlap is achieved. The operator knows when a correct height betweenthe weld torch and workpiece is achieved once the two light beamsoverlap to form a single light dot.

There may be a number of different predetermined heights the weld torchneeds to be above the workpiece for a precise weld to take place,depending on the type of workpiece being welded. The distance of thefree end of the weld torch from the weld seam can be adjusted manually,semi-automatically or automatically via an operator and/or usingprocessing means.

In one example, as shown in FIG. 7, manual adjustment means 36 can beprovided on shroud 16. Adjustment means 36 can include a pin 38 providedon arm member 4 which is slidably mounted in a curved slot 40 defined inshroud 16 adjacent attachment end 42 thereof. Recesses 44, 46 areprovided at each end of slot 40 and protrude towards the free end 26 ofthe shroud 16. The pin 38 can be slidingly moved in slot 40 and locatedin either of recesses 44, 46. The position of recesses 44, 46 eachcorresponds to the free end 8 of the weld torch being a pre-determineddifferent height from a workpiece at which beams 28, 30 will overlap toform a single light dot. In order to move the pin 38 out of a recess 44,46, the operator pushes shroud 16 towards arm member 4, thereby movingpin 38 into curved slot 40, and rotates the shroud to move the pin inthe curved slot.

In another example, the adjustment means includes one or more removablespacing elements for location between the first end of the shroud 16 andthe end 8 of the welding torch 2.

A further illumination source in the form of an LED can also bepositioned adjacent end 26 of shroud 16 to provide illumination in theweld area, thereby increasing the visibility of the weld area to anoperator. The LED is typically a different colour to the two light beamsand provides general illumination rather than a focused light beam toprevent an operator from confusing the general illumination source fromthe specific positioning aid light beams.

Referring to FIGS. 5-6 b, there is shown a positioning system in whichpositioning means similar to that described above could be used. In theabove described examples, the correct position of the torch relative toa workpiece or weld seam is achieved by moving the torch in a particularplane or axis. However, it is often the case that the entire platform onwhich the weld is to take place needs to be correctly aligned relativeto the robotic arm for precision welding and thus the robotic torchneeds to be aligned in more than 1 axis, such as the X, Y and/or Z axis.This is particularly the case for bent weld torches where the angle ofthe torch relative to the workpiece is important. Thus, in accordancewith a further aspect of the present invention, a positioning system 100is provided. The positioning system 100 includes a platform 102 in whicha number of light sensors 104 are located at pre-determined positions onor adjacent an upper surface 106 of said platform, typically in the X, Yand Z planes. When setting up the positioning of the weld torch relativeto weld platform 102, the torch is moved across the platform to follow adesired weld path. When the overlapped light beams stop over a lightsensor 104, a signal is initiated from said sensor and is transmitted toprocessing means associated with the robotic arm to inform the operatorthat correct alignment has taken place.

In order to ensure that sensor 104 is only activated when the lightbeams are overlapping, as shown in FIG. 6 a, the sensor is recessed apre-determined distance ‘d’ below upper surface 106. In addition, theside walls 105 of the platform defining the entry to the recess orchannel 107 have a narrowing taper towards sensor 104. This ensure thesensor is activated when the robotic torch is stationary and directlyoverhead (substantially vertically above sensor 104), as shown in FIG. 6a.

In use, the weld parts that are to be welded are located on the platformusing location pins 200, one of which is shown in FIG. 8 a. The locationpins are typically located at pre-determined positions on the platformand apertures defined in the weld parts are located over said locationpins in use. The positioning means of the present invention can be usedto ensure the location pins are in the correct location and the roboticarm is correctly aligned with the same.

The robotic arm is typically pre-programmed with where the location pinsshould be on the platform when in a correct weld position. Thepre-programme typically forms a master plan programme. The robotic armcan then be actuated to move to the pre-programmed position of thelocations pins. If the location pins have been moved out of alignmentfrom their correct position, when the robotic arm passes over the pointwhere the location pins should be, the light beams generated by thepositioning means will not overlap in the centre of the location pin asthey should do if the location pins are in the correct position.

For the embodiment shown in FIGS. 8 a-8 c, two sets of laser beam pairs28, 30 and 29, 31 respectively need to be provided. The laser beam pairsare typically located at substantially 90 degrees to each other. FIGS. 8b and 8 c show a top view of a location pin 200 with an upper free end202 having a narrowing taper 204 towards said free end. If the locationpin is correctly positioned, when the shroud 16 of the positioning meanslocated on the free end of the robotic arm is directly above the masterplan location pin position, the laser beams 28, 30, 29, 31 will beprojected substantially equally around the centre 202 of the locationpin 200, as shown in FIG. 8 b. If the location pin is incorrectlypositioned, laser beams 28, 30, 29, 31 will be projected in an offsetmanner from the centre 202 of the location pin 200, as shown in FIG. 8c. An operator can visually see the light beams projected onto thelocation pin and can immediately determine whether the location pinshave been moved from their correct location based on the light beamprojection on the location pin.

Thus, in the above described embodiment a cross hair arrangement ofbeams could be provided to align the location pins. The cross hairarrangement could include four spaced apart linear lines spaced atapproximately 90 degrees to each other with a central space between theinner most ends of said cross hair arrangement.

In the embodiment of FIGS. 8 a-8 c, the two pairs of laser beams (28,30;29,31) allow the positioning means (13) to be oriented both horizontallyin the X and Y directions and vertically in the Z direction. By visuallyobserving the projections of the laser beams (28,30; 29,31) relative tothe centre (202) of the location pin (200), the operator can determinewhether the positioning device is correctly oriented in the X and Ydirections. Further, by observing the height of the projections of thelaser beams (28,30; 29,31) on the tapered portion (204) of the locationpin (200), the operator can determine whether the positioning device(13) is oriented at the correct height in the Z direction.

A further problem which can result in misalignment of the weld parts forwelding is when the weld wire 10 of the robotic arm is bent. The freeend of weld wire 10 can often become bent during the set up procedure.If the weld path of a robotic weld torch is programmed for a bent wire,when the weld wire is fed from a wire feeder into the robotic arm in astraight manner, typically due to rollers being provided, the weld pathwill be wrong. As such, the positioning means of the present inventioncan be used to check whether the weld wire is bent or straight. In FIG.10 a, wire 10 is bent and the four converging light beams (only two ofwhich are shown for clarity) 28, 30 do not overlap at point 32 on thecentre of the wire 10. An operator can visually determine that theoverlapped light beams 32 are not projected onto wire 10 and theoperator therefore knows the wire is bent and needs to be trimmed. InFIG. 10 b, wire 10 is straight and the converging light beams 28, 30therefore overlap at point 32 on the wire 10, thereby informing theoperator that the wire is straight. At least four light beams aretypically required in this embodiment so that an operator can check the‘cast’ of the wire in at least four different directions. With referencenumeral 11 a mig weld wire is denoted which is fed through the weldingtorch. This can serve as a check using the light beams to ensure thatthe wire is being fed through the rollers and is being fed out straight.

It will be appreciated that any or any combination of functions of thepositioning means and/or positioning system can be fully automated ifrequired. A feedback system can be used whereby the position of thelight beams on a surface can be detected and signalled to processingmeans controlling the movement of the robotic weld torch, therebyallowing the movement or distance of the weld torch relative to thesurface to be adjusted accordingly.

With reference to FIGS. 9 a-10 b, there is illustrated a furtheradjustment mechanism for adjusting the position of the light sources ofthe positioning device relative to a weld part. In this embodiment, theshroud 16 includes an outer sleeve 300 which is movably mounted on aninner sleeve 302. The inner sleeve 302 has a channel 304 definedtherethrough to allow the weld wire to pass through the channel to allowthe ‘cast’ of the wire to be determined as described above in relationto FIGS. 10 a and 10 b.

In the illustrated embodiment, outer sleeve 300 is rotatably mounted oninner sleeve 302 via complementary screw threads 306 to allow movementof the outer sleeve relative to the inner sleeve substantiallylongitudinally of the shroud 16, as shown by arrow 308 in FIG. 9 a.Other movement mechanisms could be used, such as a sliding mechanism,pivot mechanism and/or the like.

The free end of inner sleeve 302 is provided with a plurality of movablejaw members 310 which are capable of moving in an inwardly and/oroutwardly direction substantially transverse to the longitudinal axis ofthe shroud, as shown by arrow 312. The light sources are provided in thejaw members 310 adjacent the free ends thereof. Two pairs of laser diodelight sources 22, 24 and 23, 25 are mounted at the ends of the jawmembers 310.

As outer sleeve 300 is rotated towards jaw members 310, this causes jawmembers 310 to move inwardly of each other, thereby moving the lightsources inwardly of each other. This changes the height and angle of thelight sources, thereby allowing adjustment of the operative point atwhich the light beams generated from the light sources will overlap. Asouter sleeve 300 is rotated away from jaw members 310, this causes thejaw members 310 to move outwardly of each other, thereby moving thelight sources outwardly of each other. Limiting means 314 can beprovided to limit movement of the outer sleeve in the longitudinaldirection 308. The limiting means in the illustration includes a slot316 in which a pin 318 is slidably located. Rotation of the outer sleeve300 relative to inner sleeve 302 causes pin 318 to move in slot 316, themovement of the pin being limited by the ends of slot 316. Complementarytapered surfaces 319 can be provided on the outer sleeve 300 and theinner sleeve 302 to move the jaw members 310 inwardly or outwardly asthe outer sleeve 300 is rotated relative to the inner sleeve 302.

The jaw members can be moved via resilient biasing means, via a pivottype mechanism and/or the like.

The inner sleeve 302 can be have electrical contacts or induction meansprovided at end 320 of shroud 16, as shown in FIG. 9 a, thereby allowingthe shroud to be placed in a recharging unit to recharge a power sourceassociated with shroud 16 in use.

In addition, it will be appreciated that the present invention could beused as a training aid to train welding operators to use the weldingequipment in a precise manner and to improve the weld quality. Thepositioning means and/or positioning system could signal the positionand movement of the light beams to processing means which could recordthe same, thereby providing a record of the programming movement. Thiscan be used by a trainer to help train the welding operators. Thistraining could be undertaken using a hand held weld torch or a roboticweld torch as required. An electronic test plate with sensors could beused to detect the light beams from the positioning means being directedonto the sensors. Activation of the sensors can be stored in memory andprocessing means can be used to generate a graphical representation orother suitable data feedback for the operator to allow them to see theaccuracy of their weld, weld path, programming and/or the like.

The positioning shroud is typically formed from a heat resistancematerial, such as a metal, metal alloy, durable high temperature plasticand/or the like.

It will be appreciated by persons skilled in the art that any or anycombination of the abovementioned features can be used on positioningmeans and/or in a positioning system according to the present invention.

1.-48. (canceled)
 49. A positioning device for producing a light signalto position a robot tool relative to a workpiece, comprising: a framehaving first and second opposite ends and a channel, the first end ofthe frame being attachable to an end of the robot tool; a lighting meansfor producing at least a pair of light beams projecting away from thesecond end of the frame; the lighting means comprises at least a pair oflight sources and arranged for directing the light beams therefrom inconverging directions so that the light beams intersect with each otherand provide a light signal at a predetermined distance from the secondend of the frame, characterized in that the lighting means comprises atleast two pairs of light sources to generate at least two pairs ofintersecting light beams, wherein said two pairs of intersecting lightbeams intersect at substantially the same point and wherein the lightsources are positioned around the channel and mounted at or adjacent thesecond end of the frame.
 50. The positioning device according to claim49, characterized in that the positioning device includes means foradjusting the angle or distance of the light sources to adjust the pointof intersection of the light beams.
 51. The positioning device accordingto claim 49, characterized in that the frame is in the form of a shroudand the robot tool is in the form of a robotic welding torch having anozzle, the first end of the shroud being attached to the welding torchand the second end of the shroud receiving the nozzle.
 52. Thepositioning device according to claim 49, characterized in that the pairof lighting sources is a pair of laser diode light sources.
 53. Thepositioning device according to claim 49, characterized in thatadjustment means are provided for adjusting the longitudinal position ofthe frame and/or light sources mounted on the frame relative to the endof the robot tool to adjust the distance of the intersection point ofthe light beams from the end of the robot tool.
 54. The positioningdevice according to claim 53, characterized in that limiting means areprovided to limit the longitudinal movement of the frame and/or lightsources mounted on the frame relative to the robot tool.
 55. Thepositioning device according to claim 53, characterized in that theadjustment means includes one or more removable spacing elements forlocation between the first end of the frame and the robot tool.
 56. Thepositioning device according to claim 49, characterized in thatattachment means are provided for attaching or detachably attaching theframe to the welding torch.
 57. The positioning device according toclaim 56, characterized in that the attachment means comprises a screwfitting, bayonet fitting, friction fit, one or more screws, bolts, ties,clips, inter-engaging members or the like.
 58. The positioning deviceaccording to claim 49, characterized in that the frame is rotatablymounted on the end of the robot tool.
 59. The positioning deviceaccording to claim 49, characterized in that the light sources areprovided in recesses defined in the second end of the frame.
 60. Thepositioning device according to claim 49, characterized in that lens ormagnification means are associated with the light sources to adjust thesize and/or angle of convergence of the light beams produced from saidlight sources.
 61. The positioning device according to claim 49,characterized in that each light beam pair is projected substantially 90degrees relative to the further light beam pair.
 62. The positioningdevice according to claim 49, characterized in that the frame has apower source in the form of at least one rechargeable battery, the frameincludes electrical contact means to allow engagement with complementaryelectrical contact means provided on a docking station for allowingrecharging of said battery.
 63. The positioning device according toclaim 49, characterized in that each light beam or pair of light beamsis a different color so that when said light beams overlap, a lightsignal of a further different color is produced.
 64. The positioningdevice according to claim 49, characterized in that adaptor means areprovided for engagement between the first end of the frame and the endof the robot tool.
 65. A positioning device for producing a light signalto position a robot tool relative to a workpiece, comprising: a framehaving first and second opposite ends and a channel, the first end ofthe frame being attachable to an end of the robot tool; a lighting meansfor producing at least a pair of light beams projecting away from thesecond end of the frame; the lighting means comprises at least a pair oflight sources and arranged for directing the light beams therefrom inconverging directions so that the light beams intersect with each otherand provide a light signal at a predetermined distance from the secondend of the frame, characterized in that the lighting means comprises atleast two pairs of light sources to generate at least two pairs ofintersecting light beams, wherein said two pairs of intersecting lightbeams intersect at substantially the same point and wherein adjustmentmeans are provided for adjusting the longitudinal position of the frameand/or light sources mounted on the frame relative to the second end ofthe robot tool to adjust the distance of the intersection point of thelight beams from the second end of the robot tool.
 66. The positioningdevice according to claim 65, characterized in that the frame isrotatably mounted on the end of the robot tool.
 67. A positioning devicefor producing a light signal to position a robot tool relative to aworkpiece, comprising: a frame having first and second opposite ends anda channel, the first end of the frame being attachable to an end of therobot tool; a lighting means for producing at least a pair of lightbeams projecting away from the second end of the frame; the lightingmeans comprises at least a pair of light sources and arranged fordirecting the light beams therefrom in converging directions so that thelight beams intersect with each other and provide a light signal at apredetermined distance from the second end of the frame, characterizedin that the lighting means comprises at least two pairs of light sourcesto generate at least two pairs of intersecting light beams, wherein saidtwo pairs of intersecting light beams intersect at substantially thesame point and wherein the frame is rotatably mounted on the end of therobot tool.
 68. The positioning device according to claim 67,characterized in that adjustment means are provided for adjusting thelongitudinal position of the frame and/or light sources mounted on theframe relative to the end of the robot tool to adjust the distance ofthe intersection point of the light beams from the end of the robottool.
 69. A method of using a positioning device for producing a lightsignal to position a robot tool relative to a workpiece, the positioningdevice comprising: a frame having first and second opposite ends and achannel, the first end of the frame being attachable to an end of therobot tool; a lighting means for producing at least a pair of lightbeams projecting away from the second end of the frame, the lightingmeans comprising at least a pair of light sources providing at least apair of light beams; characterized in that the method includes the stepsof directing two pairs of light beams in converging directions so thatthe light beams intersect with each other and provide a light signal ata predetermined distance from the second end of the frame, wherein saidtwo pairs of intersecting lighting beams intersect at substantially thesame point and wherein the light sources are positioned around thechannel and mounted at or adjacent the second end of the frame.
 70. Amethod for positioning a robot tool relative to a platform anddetermining whether one or more location pins are correctly positionedon the platform, by using a positioning device according to claim 49 andcharacterized by the steps of: moving the robot tool to a pre-programmedposition for the location pin; projecting the two pairs of light beamsfrom the positioning device onto the location pin; and determiningwhether the light beams are projected substantially equally around thecentre of the location pin in a correct Position or if the light beamsare projected in an offset manner from the centre of the location pin inan incorrect position.
 71. The method according to claim 70,characterized in that the two pairs of light beams are located atsubstantially 90 degrees to each other.